Every once in a while, here, you will be reminded – in a way that you would rather not be reminded – that you are living on a living volcano.

It looks like haze, but you sniff it, and . . . you’re reminded. It’s the volcanic smog known as “vog.”

Wherever Kilauea erupts, sulfur bubbles out. Hot lava cooks it with water vapor from the air (you may have done something like this over a Bunsen-burner in high-school chem.) which produces two noxious gasses. One is hydrogen sulfide, a.k.a. “rotten eggs,” which is bad enough. But the other is a choke-hazard called sulfur dioxide. When you visit Hawaii Volcanoes National Park, and the rangers have put up warning signs to keep you back from an eruption site, it’s not only because the lava crust may be too brittle to walk on. It’s also because too much hydrogen sulfide is being vented, and you’d be walking right into it.

Sometimes there’s hardly any vog from Kilauea; other times there’s a lot. The prevailing Northeast trade winds will send vog southwest over Ka’u; and if there’s enough vog, it will eddy around the southern end of Mauna Loa and drift north up the Kona coast. But once in a while the wind shifts, and a warm southerly breeze sends the vog up through Puna to Hilo, Hamakua and Kohala.

One reason people say they like to live here is that there’s no air pollution. It would be more accurate to say there are no smoggy industries here. Vog is, uhh . . . air pollution. But hey, it’s “natural!”

For current visitor access to Kilauea, The Hawaii Volcanoes National Park is at: www.nps.gov/havo